Still getting a login window

I made the ncessary setup and submitted some posts, but sometimes site visitors and I get a widnow asking for a user name and password, this window appeared with the installation process, but it's still apear till now, any ideas??

You might specify if the "window" is the BlogEngine.Net login page or a standard "authorization required" popup. If it is the "authorization required" popup, you have one or more files on the server with permission issues. Your
IIS log will have entries similar to this example line:

Access to the path
'C:\....\...\App_Data\datastore\extensions\akismetfilter.xml' is denied

I checked the folder and file permissions and it seems ok, I used to press scape when the Authorization window appers then every thing is working fine, but it cuases problems for the users, I found a huge number of errors in the log file, so how
can I solve this problem??